ERA17FA136

The pilot's decision to continue the flight into known adverse weather conditions, which resulted in spatial disorientation and a subsequent loss of airplane control and in-flight breakup.

The private pilot and three passengers departed on an instrument flight rules cross-country flight. About 2 hours into the flight, the pilot began to deviate around areas of precipitation and climbed the airplane from its previous cruise altitude of 10,000 ft mean sea level (msl) to 12,000 ft msl. Shortly thereafter, the air traffic controller told the pilot that moderate to extreme precipitation was ahead of the airplane and advised the pilot to deviate as necessary around it. Shortly thereafter, the airplane began a series of descending right turns. The controller advised the pilot to climb and maintain 12,000 ft several times; however, the airplane continued to turn and descend, and radar contact was lost at an altitude of about 2,000 ft msl. A witness reported hearing an airplane flying above, then heard a loud "boom" and saw pieces of the airplane falling from the sky. The wreckage path was about 4,550 ft in length, consistent with an in-flight breakup. Examination of the airframe and engine revealed no anomalies that would have precluded normal operation. The pilot received a weather briefing before departing on the accident flight that included a forecast for scattered severe thunderstorms along the route of flight and marginal visual flight rules conditions at the destination airport, with wind at 20 knots gusting to 30 knots, 4 miles visibility, moderate rain, and an overcast ceiling with thunderstorms in the vicinity. Although there were no hazardous weather advisories or convective SIGMETs active at the time the pilot received his preflight weather information, two of the air traffic controllers who worked the flight broadcast convective SIGMETs while the pilot was on frequency that affected the pilot's intended route of flight and called for thunderstorms with tops exceeding 40,000 ft. One of these SIGMETs was broadcast about 1 hour into the flight, and the second about 2 hours into the flight (about 40 minutes before the accident occurred). The pilot chose to continue along the flight route as weather conditions deteriorated, consistent with a common behavioral trap known as "get-there-itis." Review of weather and air traffic control radar data indicated that the airplane flew into a line of convective echoes and likely encountered instrument meteorological conditions, icing (including the possibility of supercooled large droplets), and moderate or greater turbulence about the time the airplane began the series of descending right turns that ultimately resulted in the in-flight breakup. The reduced visibility conditions and likely turbulent airmass encountered by the pilot are conducive to the development of spatial disorientation, and the in-flight breakup is consistent with the known effects of spatial disorientation. Given the severe weather conditions encountered, it is possible that the pilot's spatial disorientation was the result of an in-flight upset and significant challenges maintaining attitude control combined with the limited visibility. Toxicology testing of the pilot revealed the presence of amphetamine in lung and heart tissue. The pilot reported no conditions on his most recent application for a medical certificate, and whether the pilot was using amphetamine medicinally or illicitly could not be determined based on the available information.

An autopsy was performed on the pilot by the University of Alabama, Birmingham, Department of Pathology; the cause of death was multiple blunt force injuries. Toxicology testing performed at the FAA Forensic Sciences Laboratory identified N-propanol and ethanol at 0.046 gm/dl in muscle, but no ethanol in liver, and amphetamine in lung and heart tissue (0.114 µg/g). Ethanol is the intoxicant commonly found in beer, wine, and liquor. It acts as a central nervous system depressant. Because ingested alcohol is distributed throughout the body, levels from different postmortem tissues are usually similar. Ethanol may also be produced in body tissues by microbial activity after death; in this case levels may vary widely. Amphetamine is a Schedule II controlled substance that stimulates the central nervous system. It is available by prescription for the treatment of attention deficit disorders and narcolepsy. It carries a boxed warning about its potential for abuse and has warnings about an increased risk of sudden death and the potential for mental health and behavioral changes. Synoptic Conditions The southeast section of the National Weather Service (NWS) Surface Analysis Chart for 1300 depicted a low pressure system over Missouri at 1007-hectopascals (hPa) associated with an occluded front. Over northeast Missouri, the occluded frontal system split into a stationary front across northern Missouri eastward across Illinois, Indiana, Ohio, into Pennsylvania, and a cold front extending southward across eastern Missouri through Arkansas and into Louisiana, where the front became stationary and extended southwestward along the Texas Gulf coast. A squall line was depicted ahead of the cold front from southeastern Louisiana into southern Mississippi with an outflow boundary depicted from the end of the squall line northward across western Alabama, immediately west of the accident site at the time of the accident. The accident site was located ahead of the cold front and the outflow boundary, in the warm air sector of the front. The station models on the surface analysis chart depicted southerly winds sustained at 5 to 15 knots and broken to overcast sky cover in the area of the accident site. One station immediately south-southwest of the accident site and behind the outflow boundary reported a thunderstorm and rain showers. East of the outflow boundary, the station models indicated temperatures in the mid-to-upper 70s°F, while west of the boundary the temperatures were in the low 60s°F. Dew point temperatures were in the 50s°F to near 60°F near the Gulf Coast. Regional Radar Mosaic Weather radar depicted a line of echoes in the immediate vicinity of the accident site, which is enclosed in the red circle (see figure 1), the echoes were immediately west of Birmingham, Alabama at the time. A second more defined line of intense echoes associated with the squall line extended behind the first line from southeast Mississippi, to southeastern Louisiana, and into the Gulf of Mexico. A third area was located behind the two lines west through north of Jackson, Mississippi with an area of intense echoes. Figure 1: National Radar Mosaic Convective Outlook The morning convective outlook chart from the NWS Storm Prediction Center depicted a slight risk of organized severe thunderstorms over western Alabama, eastern Mississippi, and southeastern Louisiana during the period around the accident time, with a marginal area of thunderstorms through western Tennessee and the rest of Alabama. A slight risk indicated that an area of organized severe thunderstorms of scattered coverage was possible across the region, with either short-lived and/or isolated severe storms possible. A marginal risk indicated more isolated severe storm coverage. The convective outlook is typically used in preflight weather briefings to highlight areas where thunderstorms and severe thunderstorms can be expected. Surface Observations The closest weather reporting station was Birmingham-Shuttlesworth International Airport (BHM), located 25 miles south of the accident site at an elevation of 650 ft. The 1353 observation included wind from 160° at 14 knots gusting to 19 knots, 10 miles visibility, a few clouds at 4,700 ft above ground level (agl), broken ceiling at 6,000 ft agl, temperature 26°C, dew point temperature 13°C, altimeter 30.10 inches of mercury. Remarks included peak wind from 200° at 28 knots at 1307, and distant lightning to the northwest. The 1453 observation included wind from 260° at 16 knots, 10 miles visibility, broken ceiling at 5,500 feet agl, temperature 21°C, dew point temperature 12°C, altimeter 30.09 inches of mercury. A special weather observation issued at 1502 included wind from 260° at 17 knots gusting to 22 knots, 10 miles visibility, overcast ceiling at 4,600 ft agl, temperature 20°C, dew point temperature 12°C, altimeter 30.09 inches of mercury. Remarks included wind shift occurred at 1442, and distant lightning to the south and southwest. Preflight Weather Briefing The pilot accessed an online weather briefing through ForeFlight and filed an IFR flight plan. He obtained a low-altitude route briefing between Kissimmee, Florida, and Jackson, Tennessee, at 0606 and again at 1134, about 20 minutes before departure. The briefing included all relevant reports and forecasts, advisories, and NOTAMs for the route. The terminal forecast for BHM, which was along the route of flight, predicted marginal visual flight rules conditions with southeasterly wind at 20 knots gusting to 30 knots, with visibility 4 miles in moderate rain, overcast cumulonimbus clouds at 2,000 ft agl, and thunderstorms. At the time of the briefing, other than the AIRMETs Tango for turbulence, there were no hazardous weather advisories current for the route. A review of the briefing indicated that the convective outlook documented above was included in the information accessed by the pilot. Although there were no hazardous weather advisories or convective SIGMETs active at the time the pilot received his preflight weather information, two of the air traffic controllers who worked the flight broadcast convective SIGMETs while the pilot was on frequency that affected the pilot's intended route of flight and called for thunderstorms with tops exceeding 40,000 ft. One of these SIGMETs was broadcast about 1 hour into the flight, and the second about 2 hours into the flight (about 40 minutes before the accident occurred). In-Flight Weather Information Convective SIGMET Convective SIGMETs 60C and 61C were issued at 1255 for two areas of thunderstorms over western Alabama, Mississippi, southeastern Louisiana, and for the immediate coastal waters. Convective 60C impacted the route of flight but did not extend over the location of the accident. The advisory was current until 1455. Three sperate convective SIGMETs were issues at 1355 for portions of southwestern Alabama, southern Mississippi, and Louisiana, which were valid until 1555. In the hour prior to the accident, no Convective SIGMENTS were current for the route of flight, although the outlook area warned of potential issuance of advisories over the region. Reflectivity Figure 2 depicts the airplane's flight track overlaid on the Birmingham WSR-88D base reflectivity image for 1432 with reflectively elevation angle scans at 0.44°, 1.23° and 2.35°; respectively. Echoes of 5 to 35 dBZ or light to moderate intensity echoes along the flight track were present at all elevation scans with echoes of 45dBZ or heavy intensity echoes present within 5 miles northwest of the flight track. A strong intensity echo with reflectivity of 55dBZ or extreme intensity echoes south-southwest of the accident site was beginning to develop or surge upwards and move to the north-northeast. Figure 2: Birmingham WSR-88D Base Reflectivity Images [For additional weather inform